Pillar resistor structures for integrated circuitry

ABSTRACT

Integrated circuit structures including a pillar resistor disposed over a surface of a substrate, and fabrication techniques to form such a resistor in conjunction with fabrication of a transistor over the substrate. Following embodiments herein, a small resistor footprint may be achieved by orienting the resistive length orthogonally to the substrate surface. In embodiments, the vertical resistor pillar is disposed over a first end of a conductive trace, a first resistor contact is further disposed on the pillar, and a second resistor contact is disposed over a second end of a conductive trace to render the resistor footprint substantially independent of the resistance value. Formation of a resistor pillar may be integrated with a replacement gate transistor process by concurrently forming the resistor pillar and sacrificial gate out of a same material, such as polysilicon. Pillar resistor contacts may also be concurrently formed with one or more transistor contacts.

CLAIM OF PRIORITY

This application is a National Phase Application of, and claims priorityto, PCT Application No. PCT/US14/42865, filed on Jun. 18, 2014, titled“PILLAR RESISTOR STRUCTURES FOR INTEGRATED CIRCUITRY”, which isincorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

Embodiments of the invention generally relate to fabrication ofintegrated circuits (ICs) and monolithic devices, and more particularlypertain to resistor structures.

BACKGROUND

Monolithic ICs generally comprise a number passive devices, such asresistors, and/or active devices, such as metal-oxide-semiconductorfield-effect transistors (MOSFETs), or the like, fabricated over asubstrate. FIG. 1A is a plan view of a conventional monolithic planarresistor 110 disposed over a substrate isolation dielectric 106. FIG. 1Bis a cross-sectional view of conventional planar resistor 110. Withactive device dimensions scaling down from one technology generation tothe next, it is desirable to also scale down the footprint of resistorswithin the IC. In planar resistor 110, most of voltage drop is along aplane parallel to the substrate (e.g., x direction in FIG. 1A, 1B) ashighly resistive contacts are disadvantageous from a standpoint ofmanufacturability and/or parametric control, etc. Current densityconstraints may limit reductions in the cross-sectional area of aresistor, for example limiting reductions in the thickness T_(f) forplanar resistor 110. With the lateral length of planar resistor 110dominated by the sheet resistance of the material utilized, the resistorfootprint is a strong function of the resistance value needed for agiven circuit. Therefore, from one fabrication technology generation tothe next, circuit design constraints may prevent planar resistor 110from achieving significant area scaling. Resistor structures that offergreater scalability are therefore advantageous.

BRIEF DESCRIPTION OF THE DRAWINGS

The material described herein is illustrated by way of example and notby way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Further,where considered appropriate, reference labels have been repeated amongthe figures to indicate corresponding or analogous elements. In thefigures:

FIG. 1A is a plan view of a conventional planar resistor;

FIG. 1B is a cross-sectional view of the conventional planar resistorillustrated in FIG. 1A;

FIG. 2A is a plan view of a pillar resistor, in accordance with anembodiment;

FIG. 2B is a cross-sectional view of the pillar resistor illustrated inFIG. 2A, in accordance with an embodiment;

FIG. 2C is a circuit schematic depicting components of the resistancevalue of the pillar resistor illustrated in FIG. 2A, in accordance withan embodiment;

FIG. 2D is a plan view of a series connection of pillar resistors, inaccordance with an embodiment;

FIG. 3A is a plan view of an integrated circuit structure including atransistor and a pillar resistor, in accordance with an embodiment;

FIG. 3B is a first cross-sectional view of integrated circuit structureillustrated in FIG. 3A, in accordance with an embodiment;

FIG. 3C is a second cross-sectional view of integrated circuit structureillustrated in FIG. 3A, in accordance with an embodiment;

FIG. 4A is a flow diagram illustrating a method of forming a pillarresistor, in accordance with an embodiment;

FIG. 4B is a flow diagram illustrating a method of forming an ICinterconnect structure including a transistor and a pillar resistor, inaccordance with an embodiment;

FIGS. 5A, 5B, 5C, 5D, 5E, 5F, 5G, and 5H are cross-sectional views of anIC structure including a transistor and a pillar resistor evolving asselected operations in the method depicted in FIG. 4B are performed, inaccordance with an embodiment;

FIG. 6 illustrates a mobile computing platform and a data server machineemploying an IC structure including a pillar resistor, in accordancewith embodiments of the present invention; and

FIG. 7 is a functional block diagram of an electronic computing device,in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

One or more embodiments are described with reference to the enclosedfigures. While specific configurations and arrangements are depicted anddiscussed in detail, it should be understood that this is done forillustrative purposes only. Persons skilled in the relevant art willrecognize that other configurations and arrangements are possiblewithout departing from the spirit and scope of the description. It willbe apparent to those skilled in the relevant art that techniques and/orarrangements described herein may be employed in a variety of othersystems and applications other than what is described in detail herein.

Reference is made in the following detailed description to theaccompanying drawings, which form a part hereof and illustrate exemplaryembodiments. Further, it is to be understood that other embodiments maybe utilized and structural and/or logical changes may be made withoutdeparting from the scope of claimed subject matter. It should also benoted that directions and references, for example, up, down, top,bottom, and so on, may be used merely to facilitate the description offeatures in the drawings. Therefore, the following detailed descriptionis not to be taken in a limiting sense and the scope of claimed subjectmatter is defined solely by the appended claims and their equivalents.

In the following description, numerous details are set forth. However,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” or to “oneembodiment” means that a particular feature, structure, function, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in an embodiment” or “in one embodiment” in various placesthroughout this specification are not necessarily referring to the sameembodiment of the invention. Furthermore, the particular features,structures, functions, or characteristics may be combined in anysuitable manner in one or more embodiments. For example, a firstembodiment may be combined with a second embodiment anywhere theparticular features, structures, functions, or characteristicsassociated with the two embodiments are not mutually exclusive.

As used in the description of the invention and the appended claims, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willalso be understood that the term “and/or” as used herein refers to andencompasses any and all possible combinations of one or more of theassociated listed items.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe functional or structural relationshipsbetween components. It should be understood that these terms are notintended as synonyms for each other. Rather, in particular embodiments,“connected” may be used to indicate that two or more elements are indirect physical, optical, or electrical contact with each other.“Coupled” may be used to indicated that two or more elements are ineither direct or indirect (with other intervening elements between them)physical, optical, or electrical contact with each other, and/or thatthe two or more elements co-operate or interact with each other (e.g.,as in a cause an effect relationship).

The terms “over,” “under,” “between,” and “on” as used herein refer to arelative position of one component or material with respect to othercomponents or materials where such physical relationships arenoteworthy. For example in the context of materials, one material ormaterial disposed over or under another may be directly in contact ormay have one or more intervening materials. Moreover, one materialdisposed between two materials or materials may be directly in contactwith the two layers or may have one or more intervening layers. Incontrast, a first material or material “on” a second material ormaterial is in direct contact with that second material/material.Similar distinctions are to be made in the context of componentassemblies.

As used in throughout this description, and in the claims, a list ofitems joined by the term “at least one of” or “one or more of” can meanany combination of the listed terms. For example, the phrase “at leastone of A, B or C” can mean A; B; C; A and B; A and C; B and C; or A, Band C.

Integrated circuit structures including a pillar resistor disposed overa surface of a substrate, and fabrication techniques to form such aresistor in conjunction with fabrication of a transistor are describedherein. Following embodiments, a small resistor footprint may beachieved by orienting the resistive length of a resistor orthogonally tothe substrate surface. Such a vertically-oriented resistor “pillar” maycomplement myriad 3-D IC architectures, such as the finFET, and stackedmemory, etc. A significant benefit of building both active and passivedevices in the “z-direction” is substrate area scaling, which is ameasure on the x-y plane, for example. In embodiments, the resistorpillar is disposed over a first end of a conductive trace, a firstresistor contact is further disposed in contact with the pillar, and asecond resistor contact is disposed in contact with a second end of aconductive trace to render the resistor footprint substantiallyindependent of the resistance value, and instead predominantly dependenton contact scaling. Resistor contact dimensions are able to scale instep with transistor contact scaling. In advantageous embodiments,resistor pillar fabrication may be integrated with replacement gatetransistor (finFET or planar) processes by concurrently forming theresistor pillar and sacrificial gate out of a same material, such aspolysilicon. Pillar resistor contacts may be further formed concurrentlywith one or more transistor contacts.

FIG. 2A is a plan view of a pillar resistor 201, in accordance with anembodiment. FIG. 2B is a cross-sectional view of the pillar resistor 201along the b-b′ plane illustrated in FIG. 2A, in accordance with anembodiment. FIG. 2C is a circuit schematic depicting resistivecomponents of the pillar resistor 201, which sum to a resistance valuein accordance with an embodiment. As shown in FIGS. 2A and 2B, aconductive trace 205 is disposed over a substrate 105, with anintervening isolation dielectric material 106. In addition to pillarresistor 201, one or more active devices (not depicted), such astransistors (e.g., MOSFETs), photodetectors (e.g., PIN diodes), lasers,modulators, and the like may be similarly disposed in, on, or oversubstrate 105. In addition to pillar resistor 201, one or more otherpassive device, such as a capacitors, inductors, optical waveguides, andthe like may also be disposed in, on, or over substrate 105.

Substrate 105 may be any substrate suitable for forming a monolithicallyintegrated electrical, optical, or microelectromechanical (MEM) device,generally referred to herein as an IC. Exemplary substrates include asemiconductor substrate, semiconductor-on-insulator (SOI) substrate, aninsulator substrate (e.g., sapphire), or the like, and/or combinationsthereof. In one exemplary embodiment, substrate 105 comprises asubstantially monocrystalline semiconductor, such as, but not limitedto, silicon. Exemplary semiconductor substrate compositions also includegermanium, or group IV alloy systems, such as SiGe; group III-V systems,such as GaAs, InP, InGaAs, and the like; or group III-N systems, such asGaN.

Isolation dielectric material 106 may be any dielectric material knownin the art to be suitable for electrically isolating conductive trace205 from substrate 105. Many such materials are in use, such as, but notlimited to, silicon oxides (SiO), silicon nitrides (SiN), siliconoxynitrides (SiON), silicon carbonitrides (SiCN), and low-k materials(e.g., carbon doped silicon dioxide (SiOC), porous dielectrics, etc.).

Conductive trace 205 may be a conductive line, or pad, etc. Asillustrated in FIG. 2B, a top surface of the portion of dielectricmaterial 106 outside of, or beyond, the lateral dimension conductivetrace 205 is non-planar with a top surface of conductive trace 205. Inalternate embodiments, conductive trace 205 may be embedded withindielectric 106, with top surfaces of conductive trace 205 being eitherplanar with or covered over by dielectric material 106. Conductive trace205 may include any conductive material suitable for providing areasonably low resistance lateral conduction path and/or provide a landfor contacts of suitably low resistance. In exemplary embodiments,conductive trace 205 includes a heavily doped semiconductor and/or metalcomposition. Exemplary semiconductors include silicon, germanium, andsilicon germanium. While such semiconductor may be monocrystalline oramorphous, in the exemplary embodiment the semiconductor ispolycrystalline. Doping of conductive trace 205 may depend upon thesemiconductor material system and may render the conductive trace 205n-type or p-type. In one exemplary embodiment where conductive trace 205is polysilicon, the impurity is p-type (e.g., Boron). Impurity dopantlevel is a function of the desired sheet resistance and may for examplebe in the range of 10¹⁷-10¹⁹/cm³. In other embodiments where conductivetrace 205 is a metal, the metal composition may be any known withsuitably low sheet resistance and/or low contact resistance, such as,but are not limited to, copper (Cu), cobalt (Co), tungsten (W), titanium(Ti), aluminum (Al), platinum (Pt), nickel (Ni), and alloys thereof.

Conductive trace 205 has lateral dimensions of W₁ and L₁, which definethe lateral footprint (i.e., substrate area) of pillar resistor 201.Length L₁ is advantageously minimized to reduce the resistor footprint.In an exemplary embodiment, length L₁ is sized to just accommodate tworesistor contacts 115, 116 of minimum contact dimension CD_(C), andminimum pitch P_(C) according to the design rule for the given materiallayer. As contact dimensions and contact pitch scale with technology,these values can be expected to change over time with an exemplary rangeof CD_(A) and P_(C) each being 10-30 nm. Width W₁ is advantageouslyminimized to reduce footprint, and in an exemplary embodiment, width W₁is sized to just accommodate contacts 115, 116 of minimum contactdimension CD_(C). In other embodiments, W₁ may be increased beyondminimum contact dimension CD_(C), to accommodate misregistration orincrease conductive cross-section of conductive trace 205. Conductivetrace 205 has a z-height h₂, associated with its film thickness that mayvary as a function of the resistance desired. In an exemplarypolysilicon embodiment, h₂ may vary between 10 and 50 nm, have a widthW₁, and be doped to a level for conductive trace 205 to have anelectrical resistance of no more than 100 ohms.

In embodiments, a pillar of resistive material 210 is disposed incontact with a first end of conductive trace 205. Resistive material 210may be of any known material having a controllable sheet resistance inthe desired range and otherwise compatible with substrate processing. Inembodiments, resistive material 210 has a greater sheet resistance thandoes conductive trace 205. In further embodiments resistive material 210includes a semiconductor, such as, but not limited to, silicon,germanium, or a silicon-germanium alloy. In one exemplary embodimentwhere conductive trace 205 includes polysilicon, resistive material 210is also polysilicon, but is doped to a lower level than is conductivetrace 205 (e.g., resistive material 210 may not be intentionally doped).In other embodiments resistive material 210 includes a metal or metalalloy known to be suitable for thin film resistor applications, such as,but not limited to, tantalum, tungsten, aluminum, nickel, titanium,cobalt, their alloys, nitrides, and carbides.

The pillar of resistive material 210 extends a first z-height h₁ fromthe first end of conductive trace 205 (along z-axis). As describedfurther elsewhere herein, z-height h₁ is a function of the resistivematerial film thickness. As illustrated in FIG. 2C, the electricalresistance R₁ scales with the z-height h₁ for a given resistive materialso that a z-height h₁ may be selected for a designed resistor resistancevalue based on the resistive material selected. In certain exemplaryembodiments wherein z-height h₂ is less than 50 nm (e.g., 25 nm),z-height h₁ is in the range of 50-200 nm. In embodiments, z-height h₁may be greater than a lateral length L₂ of the pillar interfacing withconductive trace 205. In further embodiments, z-height h₁ is greaterthan the sum of lateral length L₂ and the lateral length of resistorcontact 116 (i.e., Ca). In still further embodiments, z-height h₁ isgreater than lateral length L₁ of conductive trace 205, which is furthera function of the spacing between resistive material 210 and resistorcontact 116.

Electrical resistance R₁ also scales with lateral width w₂ of the pillarof resistive material 210. In the exemplary embodiment, w₂ issubstantially equal to the critical dimension of resistor contact 115e.g., (e.g., CD_(c)) At this minimum lateral width w₂, a resistance R₁may be achieved for a given z-height h₁. This z-height may be set to bea maximum designed resistor value. Lower resistance values may beachieved for resistors fabricated to the same z-height h₁ by increasinglateral width w₂ so that the vertical resistor has a resistance valuethat is still lithographically definable. In certain embodimentstherefore, an array of vertical resistors spanning a range of a lateraldimensions may provide a range of resistance values (e.g., for trimming,etc.). In this manner, resistors with a resistance value lower than somedesigned value may incur a footprint penalty rather than footprintscaling up with increasing resistor values.

In further embodiments, as illustrated in FIG. 2D, a pillar resistorseries 202 includes a plurality of interconnected pillar resistorstructures 201A, 201B, 201N, each having the attributes of pillarresistor structure 201. Pillar resistors are linked together by an upperlevel interconnect metallization 290, for example to provide aresistance value exceeding a designed maximum resistance of pillarresistor structure 201. A single mask defining the interconnectmetallization 290 may be varied to link a very large array of verticalresistors together to form any number of resistor networks. The pillarresistor links 201A, 201B, 201N may all have the same fixed z-height(h₁) to incrementally increase a total resistance value with eachinterconnection. With each linked pillar resistor able to have aresistor pillar of arbitrary lithographically defined lateral width w₂,any total resistance value may be achieved with a discrete number ofpillar resistors (e.g., by varying w_(2a), w_(2b), w_(2n)independently).

Returning to FIGS. 2A and 2B, resistor contact 115 is disposed incontact with pillar 210 and separated from conductive trace 205 by thez-height h₁. A second resistor contact 116 is disposed in contact with asecond end of conductive trace 205. Resistor contacts 115, 116 may beknown material(s) with contact 115 advantageously providing ohmiccontact to resistor pillar 210 and contact 116 advantageously providingohmic contact to conductive trace 205. In one embodiment, resistorcontacts 115, 116 are of a same material composition. In furtherembodiments, resistor contacts 115, 116 are of the same metalcomposition, such as, but not limited to any metal, or metal alloy knownto be suitable for transistor contacts.

As shown in FIG. 2C, the electrical resistance value associated with acurrent passed between contacts 115, 116 is a function of the resistanceof resistive material 210 (R₁), resistance of conductive trace 205 (R₂),resistance of contact 115 (R_(c1)), resistance of contact 116 (R_(c2)),and resistance of contact between resistive material 210 and conductivetrace 205 (R_(c3)). Resistive voltage drop is to occur predominantlyalong the z-dimension as a strong function of resistive materialz-height h₁. In embodiments, the electrical resistance contribution ofresistive material 210 is more than twice the sum of the conductivetrace resistance R₂, first contact resistance R_(c1), second contactresistance R_(c2), and third contact resistance R_(c3). In furtherembodiments, the electrical resistance contribution of resistor pillar210 is more than three times the sum of: the conductive trace resistanceR₂; first resistor contact resistance R_(c1); second resistor contactresistance R_(c2); and third contact resistance R_(c3). In particularembodiments where both resistor pillar 210 and conductive trace 205 arepolysilicon (the latter being impurity doped for lower resistance), R₁is at least 2000Ω for a resistor pillar 210 having a z-height h₁ of atleast 50 nm while the sum of R₂, R_(c1), R_(c2), and R_(c3) is no morethan 500Ω. In certain such embodiments, conductive trace 205 has anelectrical resistance of no more than 100Ω for a material z-height(thickness) h₂ of no more than 50 nm.

FIG. 3A is a plan view of an integrated circuit structure 301 includinga transistor 302 and a pillar resistor 303, in accordance with anembodiment. FIG. 3B is a first cross-sectional view of integratedcircuit structure 301 along the b-b′ line illustrated in FIG. 3A, inaccordance with an embodiment. FIG. 3C is a second cross-sectional viewof integrated circuit structure 301 along the c-c′ line illustrated inFIG. 3A, in accordance with an embodiment. Pillar resistor 303 includesa pillar of resistive material 210 in physical and electrical contactwith resistor contact 315 and conductive trace 205. Conductive trace 205is further in physical and electrical contact with resistor contact 316.Resistive material 210 may have any or all of the attributes describedabove in the context of FIG. 2A-2C. Likewise, resistor contacts 315, 316may each have any or all of the attributes described above for resistorcontacts 215, 216. Conductive trace 205 may also have any or all of theattributes described above in the context of FIG. 2A-2C. Pillar resistor303 therefore further specifies additional embodiments of pillarresistor 201.

As shown in FIG. 3B, pillar resistor 303 includes substantially planarresistor contacts 315, 316, which have top surfaces planar with eachother. As such, resistor contact 316 has a z-dimension z-height h₃ fromconductive trace 205 that is substantially equal to the sum of theresistive material z-height h₁ and a z-dimension z-height h₄ of thefirst resistor contact 315. With a low resistance material employed forresistor contact 316, resistive drop along h₃ is negligible as it wouldbe for any filled via of comparable vertical dimension. As furtherillustrated in FIGS. 3A and 3B, resistor contact 315 interfaces with theentire top surface area of the pillar of resistive material 210 and hasa lateral length L₂ substantially equal to that of the pillar interfacewith conductive trace 205. With contact 315 landing on the fullcross-section of the pillar, contact resistance associated with contact315 may be minimized for a pillar of resistive material having across-sectional area that is a function of a minimum lateral dimensionL₂. Of further note, contact 315 is perfectly aligned to the pillar ofresistive material 210 such that the footprint of contact 315 iscoincident with the footprint of resistive material 210. As all knownlithographically-based patterning processes incur some inherent overlayerror, contact 315 is best described as belonging to a class ofstructures referred in the art as “self-aligned.” Contact 315 is“self-aligned” to resistive material 210, as described further elsewhereherein, which permits advantageous lateral scaling of IC structure 301.In certain embodiments, resistive material 210 and/or contact 316 mayrely on photolithographic pattern alignment to conductive trace 205(i.e., “non-self-aligned”). In the exemplary embodiment illustrated inFIGS. 3A, 3B, and 3C, both resistive material 210 and contact 316 arefully landed upon conductive trace 205 to ensure low correspondingcontact resistances. For a complete land, conductive trace 205 may havea lateral width w₁ that is larger than width w₂ of resistive material210 (and contact 315), and a lateral length l₁ that is larger than thesum of lateral length l₂ of resistive material 210, lateral length l₃ ofcontact 316, and intervening space s₁. Contact misregistration exceedingthe lateral dimensions of conductive trace 205 may be expected toincrease contact resistance.

In embodiments, transistor 302 is a MOSFET including a semiconductorchannel disposed under a gate stack with semiconductor source/drainregions disposed on opposite sides of the channel. In the exemplaryembodiment shown in FIGS. 3A, 3B, and 3C, transistor 302 includes one ormore non-planar semiconductor body 325 extending from substrate 105.Semiconductor body 325 may therefore be of the same substantiallymonocrystalline semiconductor as substrate 105 (e.g., silicon). Althougha finFET is exemplified in FIGS. 3A, 3B, and 3C, pillar resistors mayalso be integrated with planar transistors in substantially the samemanner described herein. Semiconductor body 325 further includes a firstsource/drain region at a first end of non-planar semiconductor body 325in electrical contact with a first source/drain contact 317.Semiconductor body 325 further includes a second source/drain region ata second end of non-planar semiconductor body 325 in electrical contactwith a second source/drain contact 318. Semiconductor body 325 furtherincludes a channel region between the two source/drain regions. Inembodiments, the pair of source/drain contacts 317, 318 havesubstantially the same composition as the first and second resistorcontacts 315, 316. In the exemplary embodiment illustrated, top surfacesof source/drain contacts 317, 318 are also planar with top surfaces ofresistor contacts 315, 316.

As further illustrated in FIGS. 3A and 3B, a gate electrode 331 isdisposed over the channel portion of semiconductor body 325. A gatedielectric (not illustrated) is disposed between gate electrode 331 andsemiconductor body 325 to complete the gate stack and enable capacitivecoupling of the channel to gate electrode 331. A second gate electrode332 is further illustrated in FIG. 3A, 3B to exemplify how pillarresistor 303 may be disposed among a plurality of transistors. Gateelectrode 331 extends a z-height h₅ from a top surface of isolationdielectric 106. In embodiments, the resistive material pillar z-heighth₁ is not greater than the gate electrode z-height h₅. In furtherembodiments, gate electrode z-height h₅ is not less than the sum of theresistive material pillar z-height h₁ and the conductive trace z-heighth₂, and not greater than the sum of the resistive material pillarz-height h₁, the conductive trace z-height h₂, and contact z-height h₄.In advantageous embodiments where resistive material 210 also serves asacrificial gate electrode material (e.g., in a gate replacement processdescribed further elsewhere herein) and contact 315 is self-aligned toresistive material 210, gate electrode z-height h₅ is greater than sumof pillar z-height h₁ and conductive trace z-height h₂.

As illustrated in FIGS. 3B and 3C, resistor contact 315 is surrounded byan isolation dielectric 340. Resistor contact 315 is similarly surroundby isolation dielectric 340 that fills space s₁ (FIG. 3A) toelectrically isolate the resistor contacts 315, 316 which may otherwiseelectrically shunt resistive material 210. Isolation dielectric 340further spaces gate electrode 331 from resistive material 210,electrically insulating transistor 302 from pillar resistor 303.Isolation dielectric 340 further spaces gate electrode 332 from resistorcontact 316 and/or conductive trace 205, electrically insulating thegate electrode 332 from pillar resistor 303. In the exemplaryembodiment, gate capping dielectric 351 is disposed over gate electrode331, planarizing the gate stack with the top surface of resistorcontacts 315, 316. In one embodiment, isolation dielectric 340 and gatecapping dielectric 351 are distinct materials allowing for etchselectively between the two materials. Either or both of isolationdielectric 340 and gate capping dielectric 351 may be of a compositiondistinct from isolation dielectric 106 allowing for etch selectivelybetween the materials. In exemplary embodiments, either or both ofisolation dielectric 340 and gate capping dielectric 351 includes one ormore of: SiO, SiON SiN, SiCN, SiC, low-k dielectric (e.g., carbon-dopedoxide), or the like.

Pillar resistors and IC structures incorporating them may be fabricatedwith a wide variety of techniques. FIG. 4A is a flow diagramillustrating a method 401 for forming a pillar resistor, in accordancewith one exemplary embodiment. Method 401 may be practiced to fabricatethe pillar resistor 201 illustrated in FIGS. 2A, 2B, or pillar resistor303 illustrated in FIGS. 3A, 3B, for example.

Method 401 begins at operation 410 where a conductive trace orinterconnect feature extending laterally over a substrate is formed, forexample over or within an insulating dielectric material. Anyfabrication technique may be utilized at operation 401. For example, aconductive material film may be deposited, a photoresist deposited overthe conductive film, and the photoresist lithography patterned to mask aportion of conductive film. The unmasked portion of conductive film maybe etched to clear and the mask removed.

Method 401 then proceeds to operation 420 where a resistive materialfilm is deposited over the conductive trace formed at operation 410. Anydeposition processes, such as, but not limited a chemical vapordeposition (CVD), plasma enhanced CVD (PECVD), physical vapor deposition(PVD), atomic layer deposition (ALD), or the like may be utilized todeposit the resistive material, for example to a film thickness of atleast 50 nm. Also at operation 420, the resistive material film ispatterned, for example with one or more photolithographic masking andetch process. A resistor pillar mask may be aligned to the conductivetrace formed at operation 410. Unmasked resistive material may then beetched to clear leaving a pillar of resistive material landed upon aportion (e.g., a first end) of the conductive trace. Optionally, beforepatterning the pillar, a recess of 10-50 nm may be etched into theresistive material film in alignment with the conductive trace formed atoperation 410. This recess may then be backfilled with a dielectricmaterial, planarized with the resistive material film, and the pillarthen etched in a self-aligned manner with the dielectric materialserving as a mask during the pillar etch.

At operation 430, a contact is formed to the resistor pillar. Anothercontact is further formed to a second end of the conductive trace atoperation 440. Operations 430 and 440 may be performed in any order, orconcurrently. In one embodiment where the pillar etch was performed witha dielectric mask, an isolation dielectric is deposited over thedielectric-masked pillar, for example by any known CVD or a spin-onprocess. If the isolation dielectric deposition process employed is notself-planarizing, the isolation dielectric may then be planarized withthe dielectric mask on the resistor pillar using any planarizationtechnique (e.g., chemical-mechanical polish). The dielectric mask on thepillar may then be removed to expose the pillar. Contact metal may thenbe backfilled onto the pillar and planarized with the isolationdielectric. In another embodiment, a self-aligned contact to theresistor pillar may be formed by first depositing an isolationdielectric over a unmasked resistor pillar, again by any known CVD or aspin-on process. If the isolation dielectric deposition process employedis not self-planarizing, the isolation dielectric may then be planarizedwith the resistor pillar using any planarization technique (e.g.,chemical-mechanical polish). The resistor pillar may then be recessed by10-50 nm relative to the isolation dielectric, for example with aselective etch process so that the pillar z-height is between 50 and 200nm. Contact metal may then be backfilled into the resistor pillarrecess.

The contact metal may be planarized with a surrounding isolationdielectric to confine the contact metal to within only the resistorpillar. In a further embodiment, a contact to the conductive trace maybe formed by further patterning the resistive material (e.g., atoperation 420) into a sacrificial pillar disposed over a second end ofthe conductive trace. This patterning may be performed concurrently withpatterning of the resistor pillar. The isolation dielectric may then bedeposited over the sacrificial pillar concurrently with the resistorpillar. The sacrificial pillar may then be subsequently removedselectively to the isolation dielectric to expose the second end of theconductive trace. Contact metal may then be backfilled into the openingleft by removal of the sacrificial pillar. Planarization of contactmetal with the isolation dielectric then also confines the contact metalto a within a via electrically isolated from the resistor pillar. Method401 then completes with interconnecting the resistor contacts to othercomponents of an IC formed over the substrate, such as but not limitedto a MOSFET gate electrode, MOSFET source/drain, or other resistors.

FIG. 4B is a flow diagram illustrating a method 402 for forming an ICstructure including a MOSFET and resistor pillar, in accordance with aspecific embodiment of method 401. Certain operations described in thecontext of method 401 are described in further detail for the exemplaryembodiment illustrated in FIG. 4B. FIGS. 5A, 5B, 5C, 5D, 5E, 5F, 5G and5H are cross-sectional views of an IC structure including a FET andresistor pillar evolving as selected operations in method 402 areperformed, in accordance with advantageous embodiments. Referencenumbers introduced in FIGS. 2A, 2B, 3A, 3B, and 3C are retained forcorresponding structures further illustrated in FIG. 5A-5H.

Referring to FIG. 4B, method 402 begins at operation 404 where atransistor semiconductor body is formed within an isolation dielectricdisposed over a substrate. In the example shown in FIG. 5A, a non-planersemiconductor body, or fin, 325 is etched into substrate 105.Semiconductor body 325 and substrate 105 may be, for example,substantially monocrystalline silicon, or any other semiconductormaterial system suitable for formation of a transistor, such as any ofthose described above. As further illustrated semiconductor body 325extends through an isolation dielectric 106, which for example may havebeen deposited over semiconductor body 325, planarized with a topsurface of semiconductor body 325, and then recessed using conventionaltechniques to expose a desired fin z-height.

Returning to FIG. 4B, at operation 405 a conductive trace is formedadjacent to the transistor semiconductor body that was formed atoperation 404. FIG. 5B illustrates an exemplary conductive (lowresistance) thin film deposited over isolation dielectric material 106using any conventional technique, such as, but not limited to PVD, CVD,or ALD. In one exemplary embodiment polysilicon is deposited by CVD. Thepolysilicon is doped in-situ or ex-situ to a desired low resistivity.The conductive thin film is then patterned, for example withconventional photolithography and etch techniques to form conductivetrace 205 extending laterally over a portion of substrate 105. Any etchsuitable for the conductive thin film may be utilized. In oneadvantageous embodiment where the conductive thin film is dopedpolysilicon and semiconductor body 325 comprises silicon, a wet etchprocess that etches doped (e.g., boron-rich) polysilicon preferentiallyover (i.e., selectively to) undoped, more lightly doped, orcomplementarily doped, silicon is employed to pattern conductive trace205.

Returning to FIG. 4B, method 402 continues at operation 406 where aresistive material is deposited over the transistor semiconductor bodyformed at operation 404, and over the conductive trace formed atoperation 405. In the exemplary embodiment illustrated in FIG. 5B, aresistive material 510 (e.g., polysilicon doped to a target resistivity)is deposited, for example to a thickness of at least 50 nm oversemiconductor 325 and over conductive trace 205. As described furtherbelow, for embodiments where resistive material 510 is to further serveas a sacrificial transistor gate in a gate replacement process,resistive material 510 may be deposited to a thickness exceeding 200 nm,as permitted by constraints on the sacrificial gate, enabling a pillarresistor to have larger maximum resistance for a given lateral pillardimension. In one exemplary embodiment, polysilicon is deposited by CVDto a thickness exceeding 50 nm, and advantageously exceeding 75 nm. Thepolysilicon is doped in-situ or ex-situ to a desired resistivity, forexample higher than that of conductive trace 205. Resistive material 510is planarized and capped with a dielectric hardmask 551, such as SiON,SiN, SiO, SiC, SiCN, SiOC, or the like.

Returning to FIG. 4B, at operation 407 the resistive material ispatterned and a recess formed over (i.e., in alignment with) theconductive trace formed at operation 405. In one exemplary embodiment, aconventional photolithography operation patterns a mask with an openingaligned to an end of the conductive trace. The exposed portion of thedielectric hardmask is etched through and a portion of the resistivematerial thickness is removed to form the recess. At operation 408 theresistive material recess formed at operation 407 is backfilled with asacrificial material. In the exemplary embodiment further illustrated inFIG. 5C, sacrificial fill material 541 is deposited in the recess etchedinto resistive material 510. Sacrificial fill material 541 may be anymaterial, such as SiON, SiN, SiO, or the like, that can be subsequentlyremoved with adequate selectively over resistive material 510. In onesuch embodiment, the sacrificial material backfilled at operation 408 isof has a composition distinct from that of dielectric hardmask 551. Anyconventional deposition process, such as CVD, ALD, or a self-planarizingspin-on process may be utilized to form sacrificial fill material 541.If the sacrificial material deposition was not self-planarizing, aplanarization operation may be subsequently performed to limitsacrificial fill material 541 to the physical confines of the recesswithin resistive material 510.

In FIG. 4B, method 402 continues with operation 409 where the resistivematerial is patterned to form a resistor pillar disposed over a firstend of the conductive trace separate from resistive material disposedover the transistor semiconductor body, which may serve as a sacrificialgate electrode. Referring to FIG. 5D, openings 509A, 509B, and 509C arepatterned through the z-height (thickness) of resistive material 510,with opening 509A exposing at least a portion of conductive trace 205which will serve to isolate pillar resistor 210 from a subsequentlyformed contact to conductive trace 205. As further illustrated in FIG.5D, an opening 509B further isolates conductive trace 205 and pillarresistor 210 from sacrificial gate 531 disposed over a channel portionof semiconductor body 325. Likewise, opening 509C further isolatesconductive trace 205 from sacrificial gate 532. In one advantageousembodiment, a photolithographicly defined mask is utilized to patternsacrificial gate 531 while the sacrificial fill material 541 is employedas a hardmask for a self-aligned pillar etch, thereby integrating thepillar resistor 210 into an existing gate-replacement process withoutincurring an additional mask layer and/or misregistration error. Forexample, a first edge of the opening 509A may delineate resistivematerial 210 without photolithography at operation 409, while a secondedge of opening 509A delineating a sacrificial resistor pillar 512 maybe the result of a photolithographic mask printed at operation 409.Likewise, opening 509B may have edges that are a union ofpreviously-delineated hardmask 541, and a photolithographic mask printedat operation 409. Opening 509C may be completely delineated withphotolithography at operation 409. Resistive material 510 may be etchedinto pillar 210, sacrificial pillar 512, and sacrificial gate 531 by anymeans known for the particular resistive material composition. In oneexample a plasma etch is utilized for patterning a resistive material ofpolysilicon.

In FIG. 4B, method 402 continues with operation 411 where isolationdielectric is deposited around the vertical resistor pillar (andsacrificial gate) formed at operation 409. Any conventional dielectricdeposition technique may be utilized at operation 411, such as, but notlimited to CVD, ALD, and spin-on processes. In the exemplary embodimentfurther illustrated in FIG. 5E, isolation dielectric 340 is depositedover sacrificial gate 531 (and hardmask 551) and resistor pillar 210(and sacrificial fill material 541). Isolation dielectric 340 may be anyknown dielectric material, such as a low-k dielectric (e.g., SiOC,etc.), or otherwise (e.g., SiCN, SiN, SiON, SiO). If isolationdielectric 340 is not deposited with a self-planarizing process, aplanarization process may be performed subsequent to deposition to bringa top surface of isolation dielectric 340 substantially planar withhardmask 551 and sacrificial fill material 541, thereby exposing a topsurface of both hardmask 551 and sacrificial fill material 541.

Returning to FIG. 4B, method 402 continues at operation 420 whereresistive material remaining over a second end of the conductive traceis removed to expose an end of the conductive trace upon which a contactis to be landed. In the exemplary embodiment illustrated in FIG. 5E, apatterned etch of hardmask portion 551 is performed to exposesacrificial pillar 512 without exposing resistor pillar 210 orsacrificial gate 531, 532. Any patterning process may be utilized atoperation 420, such as a photolithographic operation and a hardmask etchto expose resistive material 512. An etch selective to the resistivematerial (e.g., polysilicon) may then be utilized to remove sacrificialresistor pillar 512 from the surrounding isolation dielectric 340 in aself-aligned manner. As further illustrated in FIG. 5F, anothersacrificial material is backfilled into the region where resistivematerial 512 was removed to form a sacrificial pillar 542. Sacrificialpillar 542 may be of any known material that may be subsequently removedwith adequate selectively to isolation dielectric 340 such as, SiN,SiON, SiO, and the like. In one advantageous embodiment, sacrificialpillar 542 has the same material composition as sacrificial fillmaterial 541.

Returning to FIG. 4B, method 402 continues with operation 425 wheresacrificial resistive material disposed over the transistorsemiconductor body is removed as a part of a replacement gate electrodeprocess. The gate replacement process continues with backfilling theopening that resulted from removing the sacrificial resistive material.In the exemplary embodiment illustrated in FIGS. 5F and 5G, any knowngate replacement process may be performed to replace sacrificialresistive material 531 with gate electrode 331, which is part of a gatestack further including a gate dielectric (not depicted) disposedbetween gate electrode 331 and semiconductor body 325. In oneembodiment, the gate replacement process is performed in a self-alignedmanner with hardmask 551 being removed without photolithographicpatterning (e.g., with any known polish or other global etchbackprocess, or through an etch known to be selective to hardmask 551relative to isolation 340 and/or sacrificial fill material 541, and/orsacrificial pillar 542). Upon exposure of sacrificial resistive material531 and 532, selective etching is utilized to expose the channel regionof semiconductor body 325. Any known gate stack deposition process maythen be utilized to form the gate stack. For example, a high-k gatematerial, such as HfO₂, metal silicate, or the like is deposited withany suitable deposition process, such as ALD. A gate electrode material,such as one or more workfunction metal and a fill metal, is depositedover the gate dielectric, and planarized with surrounding dielectrics toform gate electrodes 331, 332. A gate recess etch and capping processmay be employed to form gate capping dielectric 351, 352.

Returning to FIG. 4B, at operation 440 the vertical resistor pillar isexposed, and a portion of the conductive trace is exposed in preparationfor contact metallization. Contact metallization is then deposited atoperation 450. In one advantageous embodiment, contact metallization ofa pillar resistor is performed concurrently with contact metallizationof a transistor source/drain. In a further embodiment, contactmetallization of a pillar resistor is fully self-aligned to a topsurface area of the resistor pillar. In the exemplary embodimentillustrated in FIG. 5H, resistor contacts 315 and 316 are formedconcurrently by removing sacrificial fill material 541 (FIG. 5G) andsacrificial pillar 542 selectively to isolation dielectric 340 andbackfilling with a desired contact metal. Recalling pillar 210 wasetched with sacrificial fill material 541 as a mask, there is thereforeno misregistration between contact metal 315 and vertical resistorpillar 210. The same contact metal may also be concurrently depositedonto a pair of semiconductor source/drain regions of semiconductor body325 disposed on opposite sides of the semiconductor channel under gateelectrode 331 (out of the z-x plane illustrated in FIG. 5H). Depositedcontact metal may then be planarized with any known process to arrive ata transistor and pillar resistor with fully metallized terminals havingtop surfaces planar with each other.

Completing discussion of FIG. 4B, method 402 then ends at operation 455with any conventional backend processing of the IC, for example byinterconnecting at least one terminal of a transistor with at least oneterminal of the pillar resistor.

FIG. 6 illustrates a system 1000 in which a mobile computing platform1005 and/or a data server machine 1006 employs an IC structure includinga vertical resistor pillar in accordance with one or more embodiment ofthe present invention. The server machine 1006 may be any commercialserver, for example including any number of high-performance computingplatforms disposed within a rack and networked together for electronicdata processing, which in the exemplary embodiment includes a packagedmonolithic IC 1050. The mobile computing platform 1005 may be anyportable device configured for each of electronic data display,electronic data processing, wireless electronic data transmission, orthe like. For example, the mobile computing platform 1005 may be any ofa tablet, a smart phone, laptop computer, etc., and may include adisplay screen (e.g., a capacitive, inductive, resistive, or opticaltouchscreen), a chip-level or package-level integrated system 1010, anda battery 1015.

Whether disposed within the integrated system 1010 illustrated in theexpanded view 1020, or as a stand-alone packaged chip within the servermachine 1006, packaged monolithic IC 1050 includes a memory chip (e.g.,RAM), or a processor chip (e.g., a microprocessor, a multi-coremicroprocessor, graphics processor, or the like) employing a verticalresistor pillar, for example as describe elsewhere herein. Themonolithic IC 1050 may be further coupled to a board, a substrate, orintegrated into a system-on-chip (SOC) 1060 along with, one or more of apower management integrated circuit (PMIC) 1030, RF (wireless)integrated circuit (RFIC) 1025 including a wideband RF (wireless)transmitter and/or receiver (TX/RX) (e.g., including a digital basebandand an analog front end module further comprises a power amplifier on atransmit path and a low noise amplifier on a receive path), and acontroller thereof 1035.

Functionally, PMIC 1030 may perform battery power regulation, DC-to-DCconversion, etc., and so has an input coupled to battery 1015 and withan output providing a current supply coupled to other functionalmodules. As further illustrated, in the exemplary embodiment, RFIC 1025has an output coupled to an antenna (not shown) to implement any of anumber of wireless standards or protocols, including but not limited toWi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20,long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM,GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as anyother wireless protocols that are designated as 3G, 4G, 5G, and beyond.In alternative implementations, each of these board-level modules may beintegrated onto separate ICs coupled to the package substrate of themonolithic IC 1050 or within a single IC coupled to the packagesubstrate of the monolithic IC 1050. In particular embodiments, at leastone of a processor IC, memory IC, RFIC, or PMIC includes logic circuitrythat incorporates a pillar resistor, and/or a transistor and pillarresistor structure, having one or more of the structural featuresdescribed elsewhere herein.

FIG. 7 is a functional block diagram of a computing device 1100,arranged in accordance with at least some implementations of the presentdisclosure. Computing device 1100 may be found inside platform 1005 orserver machine 1006, for example. Device 1100 further includes amotherboard 1102 hosting a number of components, such as, but notlimited to, a processor 1104 (e.g., an applications processor), whichmay further incorporate a pillar resistor structure, and/or a transistorand pillar resistor structure, in accordance with one or moreembodiments of the present invention. Processor 1104 may be physicallyand/or electrically coupled to motherboard 1102. In some examples,processor 1104 includes an integrated circuit die packaged within theprocessor 1104. In general, the term “processor” or “microprocessor” mayrefer to any device or portion of a device that processes electronicdata from registers and/or memory to transform that electronic data intoother electronic data that may be further stored in registers and/ormemory.

In various examples, one or more communication chips 1106 may also bephysically and/or electrically coupled to the motherboard 1102. Infurther implementations, communication chips 1106 may be part ofprocessor 1104. Depending on its applications, computing device 1100 mayinclude other components that may or may not be physically andelectrically coupled to motherboard 1102. These other componentsinclude, but are not limited to, volatile memory (e.g., DRAM),non-volatile memory (e.g., ROM), flash memory, a graphics processor, adigital signal processor, a crypto processor, a chipset, an antenna,touchscreen display, touchscreen controller, battery, audio codec, videocodec, power amplifier, global positioning system (GPS) device, compass,accelerometer, gyroscope, speaker, camera, and mass storage device (suchas hard disk drive, solid-state drive (SSD), compact disk (CD), digitalversatile disk (DVD), and so forth), or the like.

Communication chips 1106 may enable wireless communications for thetransfer of data to and from the computing device 1100. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. Communication chips 1106 may implement anyof a number of wireless standards or protocols, including but notlimited to those described elsewhere herein. As discussed, computingdevice 1100 may include a plurality of communication chips 706. Forexample, a first communication chip may be dedicated to shorter-rangewireless communications, such as Wi-Fi and Bluetooth, and a secondcommunication chip may be dedicated to longer-range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers.

While certain features set forth herein have been described withreference to various implementations, this description is not intendedto be construed in a limiting sense. Hence, various modifications of theimplementations described herein, as well as other implementations,which are apparent to persons skilled in the art to which the presentdisclosure pertains are deemed to lie within the spirit and scope of thepresent disclosure.

It will be recognized that the invention is not limited to theembodiments so described, but can be practiced with modification andalteration without departing from the scope of the appended claims. Theabove embodiments may include specific combination of features. Forexample:

In one or more first embodiment, an integrated circuit (IC) structure,comprises a conductive trace extending laterally over a substrate. TheIC structure further includes a pillar of resistive material in contactwith a first end of the conductive trace, the pillar extending a firstz-height from the first end that is greater than a lateral length of thepillar interfacing with the conductive trace. The IC structure furtherincludes a first resistor contact disposed in contact with the pillar.The IC structure further includes a second resistor contact disposed incontact with a second end of the conductive trace.

In furtherance of the one or more first embodiment, the electricalresistance of the pillar is more than twice the cumulative sum of theconductive trace resistance, first resistor contact resistance, andsecond resistor contact resistance.

In furtherance of the one or more first embodiment, the conductive tracecomprises a first material having a second z-height and a lateral lengththat is less than the first z-height, but greater than the sum of thelateral length of the pillar and a lateral length of the second resistorcontact.

In furtherance of the embodiment immediately above, the second resistorcontact has a third z-height from the second end of the conductive tracethat is substantially equal to the sum of the first z-height and afourth z-height of the first resistor contact.

In furtherance of the one or more first embodiment, first resistorcontact interfaces with the entire top surface of the pillar and has alateral length substantially equal to the lateral length of the pillarinterfacing with the conductive trace.

In furtherance of the one or more first embodiment, the pillar and theconductive trace comprise polysilicon, the conductive trace doped to ahigher impurity concentration that the pillar.

In furtherance of any one of the above embodiments, the IC structurefurther comprises a transistor disposed over the substrate and adjacentto the pillar. The transistor further comprises a gate stack disposedover a semiconductor channel, the gate stack including a gate electrodedisposed over a gate dielectric. The transistor further comprises a pairof semiconductor source/drains disposed on opposite sides of thesemiconductor channel. The transistor further comprises a pair ofsource/drain contacts disposed on the pair of semiconductorsource/drains. The conductive trace comprises a first material having asecond z-height. The gate electrode extends a z-height, from a surfaceof an isolation dielectric disposed over the substrate, greater than thesum of the first z-height and the second z-height.

In furtherance of the embodiment immediately above, the second resistorcontact has a third z-height from the second end of the conductive tracethat is approximately equal to the sum of the first z-height and afourth z-height of the first resistor contact.

In furtherance of the one or more first embodiment, the IC structurefurther comprises a transistor disposed over the substrate and adjacentto the pillar. The transistor further comprises a gate stack disposedover a semiconductor channel, the gate stack including a gate electrodedisposed over a gate dielectric. The transistor further comprises a pairof semiconductor source/drains disposed on opposite sides of thesemiconductor channel. The transistor further comprises a pair ofsource/drain contacts disposed on the pair of semiconductorsource/drains, wherein the pair of source/drain contacts havesubstantially the same composition as the first and second resistorcontacts.

In furtherance of the one or more first embodiment, the IC structurefurther comprises a transistor disposed over the substrate and adjacentto the pillar. The transistor further comprises a gate stack disposedover a semiconductor channel, the gate stack including a gate electrodedisposed over a gate dielectric. The transistor further comprises a pairof semiconductor source/drains disposed on opposite sides of thesemiconductor channel. The transistor further comprises a pair ofsource/drain contacts disposed on the pair of semiconductorsource/drains. The transistor further comprises an isolation dielectricsurrounding the pillar and first resistor contact, the isolationdielectric laterally separating the pillar from the gate electrode andfrom the second resistor contact.

In furtherance of any of the embodiments above, the first z-height is50-200 nm. A lateral length of the pillar is no more than 25 nm. Alateral length of the second resistor contact is no more than 25 nm. Theconductive trace comprises doped polysilicon having a lateral lengththat is between the first z-height and the sum of the lateral length ofthe pillar and a lateral length of the second resistor contact.

In one or more second embodiment, a system on a chip (SOC) comprisesprocessor logic circuitry. The SOC comprises memory circuitry coupled tothe processor logic circuitry. The SOC comprises RF circuitry coupled tothe processor logic circuitry and including radio transmission circuitryand radio receiver circuitry. The SOC comprises power managementcircuitry including an input to receive a DC power supply and an outputcoupled to at least one of the processor logic circuitry, memorycircuitry, and RF circuitry, wherein at least one of the processor logiccircuitry, memory circuitry, RF circuitry, or power management circuitryinclude the integrated circuit (IC) structure of any one of the aboveclaims.

In furtherance of the one or more second embodiment, the electricalresistance of the pillar is at least 2000Ω, and more than twice thecumulative sum of the conductive trace resistance, first resistorcontact resistance, and second resistor contact resistance.

In one or more third embodiment, a method of fabricating an integratedcircuit (IC) structure comprises forming a conductive trace extendinglaterally over a substrate. The method further comprises forming aresistor pillar on a first end of the conductive trace. The methodfurther comprises forming a first resistor contact disposed on thepillar. The method further comprises forming a second resistor contactdisposed on a second end of the conductive trace.

In furtherance of the one or more third embodiment, forming theconductive trace further comprises depositing a conductive film over thesubstrate and patterning the conductive film into the trace. Forming theresistor pillar on a first end of the conductive trace further comprisesdepositing a resistive material over the trace. Forming the resistorpillar further comprises patterning a recess in the resistive materialover the first end of the conductive trace. Forming the resistor pillarfurther comprises backfilling recess with a sacrificial fill material.Forming the resistor pillar further comprises patterning the resistivematerial to form the pillar aligned with the sacrificial fill material.

In furtherance of the embodiment immediately above, forming the firstresistor contact further comprises depositing an isolation dielectricaround the resistor pillar. Forming the first resistor contact furthercomprises removing the sacrificial fill material selectively to theisolation dielectric to expose the pillar. Forming the first resistorcontact further comprises depositing a contact metal onto the exposedresistor pillar. Forming the second resistor contact further comprisespatterning the resistive material to form a sacrificial pillar disposedover the second end of the conductive trace concurrently with patterningthe resistor pillar. Forming the second resistor contact furthercomprises removing the sacrificial pillar selectively to the isolationdielectric to form a via landing on the second end of the conductivetrace. Forming the second resistor contact further comprises depositingthe contact metal onto an exposed end of the conductive traceconcurrently with depositing the contact metal onto the exposed resistorpillar.

In furtherance of the embodiment above, the method further comprisesforming a transistor over the substrate adjacent to the resistor pillar.Forming the transistor further comprises forming a semiconductor channelregion. Forming the transistor further comprises forming a gate stackdisposed over the semiconductor channel, the gate stack including a gateelectrode disposed over a gate dielectric. Forming the transistorfurther comprises forming a pair of semiconductor source/drains disposedon opposite sides of the semiconductor channel Forming the transistorfurther comprises forming a pair of source/drain contacts disposed onthe pair of semiconductor source/drains. Forming the pair ofsource/drain contacts further comprises depositing the contact metalonto the semiconductor source/drains concurrently with depositing thecontact metal onto the exposed resistor pillar.

In furtherance of the embodiment immediately above, the method furthercomprises forming a transistor over the substrate adjacent to theresistor pillar. Forming the transistor further comprises forming asemiconductor channel region. Forming the transistor further comprisesforming a gate stack disposed over the semiconductor channel, the gatestack including a gate electrode disposed over a gate dielectric.Forming the gate stack further comprises depositing the resistivematerial over the semiconductor channel Forming the gate stack furthercomprises patterning the resistive material over the semiconductorchannel into sacrificial gate. Forming the gate stack further comprisesremoving the sacrificial gate after depositing the isolation oxidearound the resistor pillar and around the sacrificial gate. Forming thegate stack further comprises forming a pair of semiconductorsource/drains disposed on opposite sides of the semiconductor channelForming the gate stack further comprises forming a pair of source/draincontacts disposed on the pair of semiconductor source/drains.

In furtherance of any of the third embodiments above, depositing theconductive film over the substrate further comprises depositing animpurity doped polysilicon film over the substrate. Depositing theresistive material over the trace further comprises depositing a morelightly doped polysilicon film over the doped polysilicon film.

In furtherance of any of the third embodiments above, depositing theconductive film over the substrate further comprises depositing animpurity doped polysilicon film over the substrate. Depositing theresistive material over the trace further comprises depositing a morelightly doped polysilicon film over the doped polysilicon film. Formingthe first resistor contact disposed on the pillar further comprisesbackfilling a first recess self-aligned to the pillar with contactmetal. Forming the second resistor contact disposed on a second end ofthe conductive trace further comprises backfilling a second recessapproximately equal in z-height to the sum of the first resistor contactand pillar with the contact metal.

However, the above embodiments are not limited in this regard and, invarious implementations, the above embodiments may include theundertaking only a subset of such features, undertaking a differentorder of such features, undertaking a different combination of suchfeatures, and/or undertaking additional features than those featuresexplicitly listed. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. An integrated circuit (IC) structure, comprising:a conductive trace extending laterally over a substrate; a pillar ofresistive material in contact with a first end of the conductive trace,the pillar of resistive material extending a first z-height from thefirst end of the conductive trace that is greater than a lateral lengthof the pillar of resistive material interfacing with the conductivetrace; a first resistor contact disposed in contact with the pillar ofresistive material; and a second resistor contact disposed in contactwith a second end of the conductive trace, wherein electrical resistanceof the pillar of resistive material is more than twice a cumulative sumof conductive trace resistance, first resistor contact resistance, andsecond resistor contact resistance.
 2. The IC structure of claim 1,wherein the conductive trace comprises a first material having a secondz-height and a lateral length that is less than the first z-height, butgreater than a sum of the lateral length of the pillar of resistivematerial and a lateral length of the second resistor contact.
 3. The ICstructure of claim 2, wherein the second resistor contact has a thirdz-height from the second end of the conductive trace that issubstantially equal to a sum of the first z-height and a fourth z-heightof the first resistor contact.
 4. The IC structure of claim 1, whereinthe first resistor contact interfaces with an entire top surface of thepillar of resistive material and has a lateral length substantiallyequal to the lateral length of the pillar of resistive materialinterfacing with the conductive trace.
 5. The IC structure of claim 1,wherein the pillar of resistive material and the conductive tracecomprise polysilicon, the conductive trace is doped to a higher impurityconcentration that the pillar of resistive material.
 6. The IC structureof claim 1, further comprising a transistor disposed over the substrateand adjacent to the pillar of resistive material, the transistor furthercomprising: a gate stack disposed over a semiconductor channel, the gatestack including a gate electrode disposed over a gate dielectric; a pairof semiconductor source/drains disposed on opposite sides of thesemiconductor channel; and a pair of source/drain contacts disposed onthe pair of semiconductor source/drains; and wherein: the conductivetrace comprises a first material having a second z-height; and the gateelectrode extends a z-height, from a surface of an isolation dielectricdisposed over the substrate, greater than sum of the first z-height andthe second z-height.
 7. The IC structure of claim 6, wherein the secondresistor contact has a third z-height from the second end of theconductive trace that is approximately equal to sum of the firstz-height and a fourth z-height of the first resistor contact.
 8. The ICstructure of claim 1, further comprising a transistor disposed over thesubstrate and adjacent to the pillar of resistive material, thetransistor further comprising: a gate stack disposed over asemiconductor channel, the gate stack including a gate electrodedisposed over a gate dielectric; a pair of semiconductor source/drainsdisposed on opposite sides of the semiconductor channel; and a pair ofsource/drain contacts disposed on the pair of semiconductorsource/drains, wherein the pair of source/drain contacts havesubstantially same composition as the first and second resistorcontacts.
 9. The IC structure of claim 1, further comprising: atransistor disposed over the substrate and adjacent to the pillar ofresistive material, the transistor further comprising: a gate stackdisposed over a semiconductor channel, the gate stack including a gateelectrode disposed over a gate dielectric; a pair of semiconductorsource/drains disposed on opposite sides of the semiconductor channel;and a pair of source/drain contacts disposed on the pair ofsemiconductor source/drains; and an isolation dielectric surrounding thepillar of resistive material and the first resistor contact, theisolation dielectric laterally separating the pillar of resistivematerial from the gate electrode and from the second resistor contact.10. The IC structure of claim 1, wherein: the first z-height is 50-200nm; a lateral length of the pillar of resistive material is no more than25 nm; a lateral length of the second resistor contact is no more than25 nm; and the conductive trace comprises doped polysilicon having alateral length that is between the first z-height and a sum of thelateral length of the pillar of resistive material and a lateral lengthof the second resistor contact.
 11. A method of fabricating anintegrated circuit (IC) structure, the method comprising: forming aconductive trace extending laterally over a substrate; forming aresistor pillar on a first end of the conductive trace; forming a firstresistor contact disposed on the resistor pillar; and forming a secondresistor contact disposed on a second end of the conductive trace,wherein: forming the conductive trace further comprises depositing aconductive film over the substrate and patterning the conductive filminto the conductive trace; forming the resistor pillar on a first end ofthe conductive trace further comprises: depositing a resistive materialover the conductive trace; patterning a recess in the resistive materialover the first end of the conductive trace; backfilling the recess witha sacrificial fill material; and patterning the resistive material toform the resistor pillar aligned with the sacrificial fill material. 12.The method of claim 11, wherein: forming the first resistor contactfurther comprises: depositing an isolation dielectric around theresistor pillar; removing the sacrificial fill material to expose theresistor pillar; and depositing a contact metal onto the exposedresistor pillar; and forming the second resistor contact furthercomprises: patterning the resistive material to form a sacrificialpillar disposed over the second end of the conductive trace; removingthe sacrificial pillar selectively to the isolation dielectric to form avia landing on the second end of the conductive trace; depositing thecontact metal onto an exposed end of the conductive trace concurrentlywith depositing the contact metal onto the exposed resistor pillar. 13.The method of claim 11, further comprising forming a transistor over thesubstrate adjacent to the resistor pillar, wherein forming thetransistor further comprises: forming a semiconductor channel region;forming a gate stack disposed over the semiconductor channel, the gatestack including a gate electrode disposed over a gate dielectric;forming a pair of semiconductor source/drains disposed on opposite sidesof the semiconductor channel; and forming a pair of source/draincontacts disposed on the pair of semiconductor source/drains, whereinforming the pair of source/drain contacts further comprises: depositingthe contact metal onto the semiconductor source/drains concurrently withdepositing the contact metal onto the exposed resistor pillar.
 14. Themethod of claim 12, further comprising forming a transistor over thesubstrate adjacent to the resistor pillar, wherein forming thetransistor further comprises: forming a semiconductor channel region;forming a gate stack disposed over the semiconductor channel, the gatestack including a gate electrode disposed over a gate dielectric,wherein forming the gate stack further comprises: depositing theresistive material over the semiconductor channel; patterning theresistive material over the semiconductor channel into sacrificial gate;removing the sacrificial gate after depositing the isolation oxidearound the resistor pillar and around the sacrificial gate; forming apair of semiconductor source/drains disposed on opposite sides of thesemiconductor channel; and forming a pair of source/drain contactsdisposed on the pair of semiconductor source/drains.
 15. The method ofclaim 11, wherein: depositing the conductive film over the substratefurther comprises depositing an impurity doped polysilicon film over thesubstrate; and depositing the resistive material over the conductivetrace further comprises depositing a more lightly doped polysilicon filmover the doped polysilicon film.
 16. The method of claim 11, wherein:depositing the conductive film over the substrate further comprisesdepositing an impurity doped polysilicon film over the substrate;depositing the resistive material over the conductive trace furthercomprises depositing a more lightly doped polysilicon film over thedoped polysilicon film; forming the first resistor contact disposed onthe resistor pillar further comprises backfilling a first recessself-aligned to the resistor pillar with the contact metal; and formingthe second resistor contact disposed on a second end of the conductivetrace further comprises backfilling a second recess approximately equalin z-height to sum of the first resistor contact and the resistor pillarwith the contact metal.
 17. A system on a chip (SOC), comprising:processor logic circuitry; memory circuitry coupled to the processorlogic circuitry; RF circuitry coupled to the processor logic circuitryand including radio transmission circuitry and radio receiver circuitry;and power management circuitry including an input to receive a DC powersupply and an output coupled to at least one of the processor logiccircuitry, memory circuitry, and RF circuitry, wherein at least one ofthe processor logic circuitry, memory circuitry, RF circuitry, or powermanagement circuitry include an integrated circuit (IC) structure,comprising: a conductive trace extending laterally over a substrate; apillar of resistive material in contact with a first end of theconductive trace, the pillar of resistive material extending a firstz-height from the first end of the conductive trace that is greater thana lateral length of the pillar of resistive material interfacing withthe conductive trace; a first resistor contact disposed in contact withthe pillar of resistive material and separated from the conductive traceby a first thickness; and a second resistor contact disposed in contactwith a second end of the conductive trace, wherein electrical resistanceof the pillar of resistive material is at least 2000Ω and more thantwice a cumulative sum of conductive trace resistance, first resistorcontact resistance, and second resistor contact resistance.